EFFECTS OF INTERFERON-ALPHA, INTERFERON-BETA AND INTERFERON-GAMMA ON THE FUNCTION OF DIFFERENTIATED LEUKEMIC HL-60 CELLS INDUCED BY 1,25-DIHYDROXYVITAMIN D-3

The differentiation of HL-60, a human leukemic cell line, into monocyt e-like cells (D-3-HL-60 cells) is induced by 1,25-dihydroxyvitamin D-3 (D-3) We examined the effects of interferon (IFN) treatment of D-3-HL -60 cells on the expression of cell surface antigens, the phagocytic a ctivity for fluorescent beads, production of oxygen radicals, and intr acellular growth of Legionella pneumophila, Activation of D-3-HL-60 ce lls with IFN-gamma, beta, and alpha for 24 h significantly increased e xpression of CD16, CD36, CD71, and HLA-DR antigens, IFN-gamma markedly enhanced the phagocytic activity of beads in D-3-HL-6O cells, There w as no significant difference in phagocytic activity between cells expo sed to IFN-alpha or beta and untreated D-3-HL-60 cells, IFN-alpha, bet a, and gamma enhanced production of oxygen radicals, including superox ide, by D-3-HL-60 cells, Superoxide production was enhanced to the gre atest degree by IFN-gamma followed by IFN-beta and then IFN-gamma. Int racellular growth of L. pneumophila in D-3-HL-60 cells was inhibited b y interferons (IFN-gamma > beta> gamma), Similar results were obtained in human mononuclear cells, These data indicate that interferons can act as biologic response modifiers not only in human mononuclear cells but also in differentiated leukemic cells, Our results may have impli cations for the development of differentiation therapy for treatment o f leukemia.